Atomic layer deposition (ALD) is a deposition technique used for the deposition of material layers over features formed on substrates. One example of an ALD process includes the sequential introduction of pulses of gases. For instance, one cycle for the sequential introduction of pulses of gases may contain a pulse of a first reactant gas, followed by a pulse of a purge gas and/or a pump evacuation, followed by a pulse of a second reactant gas, and followed by a pulse of a purge gas and/or a pump evacuation. A pulse of a purge gas and/or a pump evacuation between the pulses of the first reactant gas and the pulses of the second reactant gas serves to reduce the likelihood of gas phase reactions of the reactants due to excess amounts of the reactants remaining in the chamber.
The gases may be provided to the chamber through a showerhead including an inner blocker plate to distribute the gases within the showerhead prior to reaching the face of the showerhead, through which the gases enter the process chamber. Conventional blocker plates utilized in such chambers typically include many small holes used to distribute the precursors to within the showerhead. However, the inventors have observed that because of the high flow resistance exhibited from such blocker plates, the second precursor is often supplied before the first precursor is completely purged.
Therefore, the inventors have provided improved blocker plate for use in substrate processing chambers.